Landing zone inertial latch

ABSTRACT

A landing zone inertial latch which prevents the rotation of an actuator arm of a disc drive following a shock and has a latch mechanism whose axis is perpendicular to the central axis of the actuator arm. The latch mechanism is self-energizing so that the latch remains out of the way during normal operation of the inertial latch, but then is energized by the shock to prevent the actuator arm and, in particular, the transducer from leaving the landing zone during a shock. The landing zone inertial latch is small and compact since the inertia of the latch is not required to hold the actuator arm. A landing zone inertial latch is also provided which can prevent rotation of the actuator arm in either direction.

This is a division of application Ser. No. 08/182,246, filed Jan. 13,1994, now abandoned.

BACKGROUND OF THE INVENTION

In a fixed disc hard disc drive which are common to personal computers,the disc drive actuator and recording heads must be prevented fromsudden movements when the disc drive is powered down in order to preventdamage to the disc recording media. This is a particular problem indrives using a voice coil motor; when the disc drive is powered down,there is no force which will prevent the recording heads from moving outof a landing zone and into areas of the recording media where data isstored and hitting the disc surface causing data loss. This isespecially true with notebook and portable computers which arefrequently moved and jostled.

Initially, the disc drive actuator arm was held in place by a physicallock which prevented movement. The problem with a physical lock is thatit can fail in the locked position and prevent any further use of thedisc drive until repaired. Also, a physical lock requires its own powersource which increases power demand within the disc drive and increasesthe heat generated by the disc drive. These physical locks were oftenused for 3.5" disc drives since the drives were very large and couldhouse a large power supply easily.

However, with the introduction of notebook and portable computers, harddisc drives needed to be much smaller, lighter and consume less power.The extra power required by a physical lock could no longer be toleratedand the excess heat generated by a larger power supply could not beadequately dissipated, In addition, since the newer hard disc drives aredesigned to be lightweight, the addition weight for the power supplyneeded for a physical lock can not be tolerated. Also, the extra spacerequired by the larger power supply and the physical lock is notdesirable.

After physical locks, ramp latches were introduced which did not requirean independent power supply and were smaller in size. These ramplatches, however, required a ramp onto which the actuator arm was lockedand required a physical lock to lock the actuator arm onto the ramp.Thus, if the physical lock failed, the disc drive would be inoperativeuntil repaired.

After ramp latches, inertial latches were introduced which used theinertia of the latch to offset the inertia of the actuator arm and stopthe movement of the actuator arm. These prior art inertial latches,however, were large since the lock itself held the actuator arm steady.In addition, the prior inertial latches were large since the inertia ofthe latch itself had to be large enough to balance and counteract thehuge inertia of a large heavy actuator arm assembly.

SUMMARY OF THE INVENTION

Thus, it is an object of the present invention to provide a landing zoneinertial latch mechanism for a hard disc drive which can preventactuator arm movement in both rotary directions.

It is another object of the present invention to provide a landing zoneinertial latch which is light-weight, but can stop an actuator arm underany rotary shocks.

It is another object of the present invention to provide a landing zoneinertia latch which is small and compact so that it may be located atnumerous places within the disc drive housing.

It is another object of the present invention to provide a landing zoneinertial latch which latches onto the actuator arm so that the inertialmass of the landing zone inertial latch can be minimal such that thelanding zone inertial latch is small and compact.

These and other objects of the present invention are provided by alanding zone inertial latch which latches onto the actuator arm so thatthe inertia of the latch may be less than the inertial of the actuatorarm such that the landing zone inertial latch is small and compact. Inaddition, the landing zone inertial latch is self-energizing and is keptin a storage position during normal operation of the disc drive. Finallythe landing zone inertial latch may be perpendicular to the axis ofrotation of the actuator arm and can move to prevent actuator arm motionin response to any shock.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional objects and features of the present invention will be morereadily apparent from the following detailed description and theappended claims when taken in conjunction with the drawings, in which:

FIG. 1 is a schematic view of a typical actuator assembly which has afirst embodiment of the landing zone inertial latch of the presentinvention attached to it;

FIG. 2 is an exploded top view of the landing zone inertial latch shownin FIG. 1;

FIG. 3 is a three dimensional top view of a second embodiment of thelanding zone inertial latch of the present invention;

FIG. 4 is a perspective view of the U-shaped holder of the secondembodiment of the present invention; and

FIG. 5 is an exploded schematic view showing how the parts of the secondembodiment of the present invention are connected together.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

A first embodiment of the present invention will now be provided withreference to FIGS. 1 and 2. First, FIG. 1 shows a typical hard discdrive with the claimed landing zone inertial latch installed. Thehousing 10 of the disc drive is sealed which keeps contaminants, such asdust, away from delicate components of the hard disc drive. If acontaminant, such as a particle of dust enters the housing and lands onthe disc drive magnetic media, the hard disc drive may crash. Thus, allof the components of a typical hard disc drive are contained within thesealed housing 10. A magnetic recording medium 20 is shown. Therecording medium 20 has concentric tracks of magnetic particles whichare used to store data. In order to access all of the tracks of therecording media 20, a disc drive spindle motor is attached to the centerof the recording medium and causes the recording medium 20 to spin at acertain angular velocity. The spindle motor, which is located underneaththe recording medium 20, is not shown for clarity. The recording medium20 also has a landing zone 30 where no data tracks are located and thepowered down recording heads can sit without damaging the recordingmedium.

To record data to the recording medium and read data from the recordingmedium 20, an actuator arm assembly 40 is used. The various componentsof the actuator arm assembly operate to move a transducer 50 (recordinghead) across the tracks of the recording medium 20 and to read and/or towrite data from/to the recording medium 20. More specifically, theactuator arm assembly 40 includes an actuator arm 70, a flexure 60 and aslider with a recording head 50. The recording heads 50 are the elementof the actuator arm assembly 40 which actually read and write data toand from the recording medium in a convention manner. The recordingheads 50 fly above the recording media 20 on a cushion of air which isgenerated by the rotation of the recording media. The cushion of air isless than one micrometer thick. The flexure 60, which is attached to therecording head 50 biases the recording head 50 down towards therecording media 20. The actuator arm 70, which is attached to theflexure 60, connects the flexure and the recording head 50 to a voicecoil motor which rotates the actuator arm assembly 40 about a pivotpoint 45 in response to electrical signals from the drive controller.The voice coil motor operates in a convention manner and will not befurther described. When the disc drive is powered up, the voice coilmotor will hold the actuator arm assembly steady at a defined, targetedposition by a magnetic force generated by the voice coil magnets.However, when the disc drive is powered down, the voice coil motor doesnot generate a magnetic force and does not prevent the actuator arm frommoving.

The part of the voice coil motor attached to the actuator arm assembly40 is typically a voice coil 90. The voice coil motor also has voicecoil motor magnets which are attached to the housing of the disc driveand are located directly above and below the voice coil 90 and are notshown for clarity reasons. There is also a voice coil overmold 80 whichprotects the voice coil 90 from damage. The voice coil magnets and thevoice coil 90 together make up the voice coil motor which rotates theactuator arm assembly 40 using magnetic forces. The location of the coiland magnets could also be reversed i.e., the magnet carried on the arm,without changing the usefulness of this invention.

One embodiment of the landing zone inertial latch mechanism 95 of thepresent invention will now be described with reference to FIG. 1 whichshows a typical hard disc drive actuator with an embodiment of thepresent invention and FIG. 2 which is an exploded top view of anembodiment of the present invention. The landing zone inertial latch 95operates to keep the recording heads 50 of the actuator arm assemblywithin the landing zone 30 while the disc drive is powered down in orderto prevent data loss. While the disc drive is powered up, the actuatorarm and the recording heads are restrained by the force of the voicecoil motor.

The landing zone inertial latch 95 prevents unrestrained movement of therecording heads and prevents recording media damage following a shock.For example, the landing zone inertial latch will prevent the coilovermold 90 and the entire actuator assembly from rotating by latchingonto a pair of protrusions 130, 131 on the overmold 90. When theactuator assembly attempts to rotate clockwise, the actuator assemblywill be prevented from moving because protrusion 131 will hit thelanding zone inertial latch 95. On the other hand, if the actuatorassembly rotates in a counter clockwise direction, the protrusion 130 islatched onto by the landing zone inertial latch and prevented frommoving. Thus, this embodiment of the present invention prevents theactuator arm assembly and the recording heads from moving in eitherrotary direction.

The landing zone inertial latch 95 includes a U-shaped piece ofnon-magnetic material 100 which latches onto a pair of protrusions 130,131 on the overmold 90 and prevent rotation of the actuator assembly asdescribed above. This piece of non-magnetic material 100 is connectedthrough a non-magnetic pivot pin 110 to a non-magnetic elongated portion105 which is located beneath the voice coil overmold 90 and the voicecoil 80. The non-magnetic pieces may also be brass. The elongatedportion 105 has a magnetic insert 120 which is located inside of theelongated portion. The magnetic insert 120 is the only piece of thelanding zone inertial latch which is magnetizable. The magnetic insert120 is located beneath the voice coil 80 as well. The magnetic insert120 operates to keep the landing zone inertial latch 95 in a storageposition during normal operation of the disc drive by being attracted tothe voice coil magnet's magnetic flux and causing the landing zoneinertial latch to be automatically aligned to the voice coil magnetswhich holds the landing zone inertial latch in a storage position. Themagnetic flux of the voice coil magnets acts as a bias force therebymaking it unnecessary to have a physical bias spring within the system.Thus, this embodiment of the present invention is self-energizing anddoes not require any power source.

Now, a detailed description of the operation of the embodiment oflanding zone inertial latch will be described. When a shock causes theactuator assembly and overmold to move in a clockwise direction, severalevents occur. First, the elongated portion 105 of the landing zoneinertial latch 95 overcomes the bias force induced by the magnetic fluxof the voice coil magnet in the magnetic insert 120 and rotates in acounterclockwise direction about pivot pin 110. This counterclockwiserotation of the elongated portion 105 causes the left side the latchpiece 100 to move down towards the overmold 90 and position A. Then, asthe actuator assembly and the overmold 90 rotate clockwise in responseto the shock, the protrusion 130 of the overmold 90 is latched by theleft side of the latch piece and the entire actuator assembly isprevented from moving further and the recording heads are prevented frommoving outside of the landing zone 30. When the shock and rotation hassubsided, the landing zone inertial latch 95 will return to itsinoperative storage position until another shock occurs.

If a shock causes the actuator assembly to begin to rotate in acounterclockwise fashion, then the elongated portion 105 will overcomethe bias force of the voice coil magnet and rotate in clockwise fashionabout pivot point 110. This clockwise rotation of the elongated portion105 will cause the right side of the latch piece 110 to move downtowards the overmold 90 toward position B. Thus, the right side of thelatch piece 100 will catch the protrusion 131 and the prevent theactuator assembly from moving any farther which in turn prevents therecording head 50 from moving outside the landing zone 30 and causingdata loss. This embodiment provides a number of advantages: rotation inboth directions is controlled; arm rotation during torsional shock isprevented; arm rotation in the event of direct or lateral shock iscontrolled; regardless of whether the coil end or head end is heavy; thelatch piece automatically aligns to the VCM magnet; and there is no needto include a physical spring in the system, as the VCM magnet leakageprovides the force to resolve alignment.

A second embodiment of the landing zone inertial latch of the presentinvention will now be described with reference to FIGS. 3, 4 and 5. FIG.3 shows a three dimensional top view of a second embodiment of thepresent invention which is also a landing zone inertial latch. Thisembodiment also operates to keep the recording heads within the landingzone during a shock to the powered down disc drive. FIG. 3 shows therecording medium 20 which has a landing zone 30. There is no datalocated within the landing zone 30 so that the recording head 50 can siton the recording media within the landing zone 30 without destroying anydata. The structure of the actuator arm assembly is the same as theprevious embodiment and will not be described here again.

As in the previous embodiment, the voice coil 90 has an overmold 80which protects the coils 90 from any damage. The overmold 80 also has alatch pin 240 which is fixedly attached to the overmold 80. Theoperation of the latch pin 240 will be described below in connectionwith the discussion of the operation of this embodiment of the landingzone inertial latch.

The landing zone inertial latch has a U-shaped support piece 200 whichholds the rest of the components of the landing zone inertial latch. Thesupport piece 200 is attached to the housing 10. A more detailed view ofthe U-shaped support piece is shown in FIG. 4. The support piece 200 islocated below the voice coils 90 and overmold 80. The support piece 200has two holes drilled in opposite sides of the piece. A pin 210 fitsthrough these holes and .secures an inertial mass 220 to the supportpiece 200 and allows the inertial mass 220 to rotate with respect to thesupport piece. The inertial mass 220 includes an impact member 230having an impact surface 235; the impact member 230 is fixedly attachedto the inertial mass 220. A more detailed view of the physicalinterconnections between the various components of the second embodimentof the landing zone inertial latch is shown in FIG. 5. As shown in FIG.3, the major axis of the actuator arm assembly 40 and the axis ofrotation of the landing zone inertial latch are at right angles to eachother. This perpendicular orientation allows the landing zone inertiallatch to occupy little space. Also the perpendicular orientation allowsthe inertial mass 220 to be much smaller since the inertial mass is onlybe utilized to move the latch pin into position.

While the disc drive is not being subjected to a shock, the inertialmass 220 is biased by a bias spring (not shown but located on the axisof the pin 210) into a storage position so that the inertial latch willnot affect normal operation of the actuator arm assembly.

When a shock occurs, an unlatched powered down recording head 50 isprone to move outside of the landing zone and destroy data. For example,the actuator arm assembly may rotate in a direction as shown by arrow250. To prevent this unwanted movement, the shock which causes theactuator arm to rotate in a direction shown by arrow 250 also causes theinertial mass 220 to overcome the bias force of the spring and rotateclockwise. This clockwise rotation of the inertial mass 220 causes theimpact surface 235 to rotate upwards and stop in the path of the latchpin 240 which is fixedly attached to the overmold. The impact surface235 will stop the movement of the latch pin 240 which in turn stops themovement of the actuator arm 40. Thus, the recording heads 50 of theactuator assembly 40 are prevented from moving outside of the landingzone 30. It should be noted that the landing zone inertial latch isself-energizing and will remain closed for the duration of the shock dueto the force which the latch pin 240 is exerting upon the impact surface235.

Once the shock has passed, the biasing force of the spring will returnthe landing zone inertial latch to its storage position out of the wayof the actuator arm assembly. In particular, the impact surface 235 willrotate downwards with the inertial mass 220 and into a storage positionout of the path of the latch pin 240. Then, when another shock occurs,the landing zone inertial latch will rotate again to stop unwantedmovement. Since the present invention does not require any power sourceand the inertial mass 220 is small, the inertial latch can re-energizeitself repeatedly without much lag time.

It should be noted that the inertial mass of the landing zone inertiallatch is much smaller than the inertial mass of a typical inertiallatch. This smaller inertial mass allows the present landing zoneinertial latch to be smaller, compact and have a faster reaction time.The inertial mass is smaller for several reasons. First, the inertialmass of the landing zone inertial latch causes the rotation of thelanding zone inertial latch and does not have to be large enough tocounteract the huge inertial of the actuator arm assembly. Second, thelanding zone inertial latch uses the force between the latch pin and theimpact surface to hold the latch closed during a shock and does not haveto be able to hold the actuator arm using its own inertia.

If a shock occurs which causes the recording heads 50 and actuator armassembly 40 to move in the opposite direction, towards the center of thelanding zone, the actuator arm assembly will be stopped by a crash stopand does not require that the inertial latch stop the arm. Thus, thisembodiment of the present invention only prevents rotation of therecording heads away from the landing zone. However, due to theperpendicular orientation of the actuator arm and the landing zoneinertial latch, this embodiment of the landing zone inertial latch issmall and compact and can be placed at many locations within the discdrive housing.

While the claimed invention has been described with reference to a fewspecific embodiments, the description is illustrative of the inventionand is not to be construed as limiting the invention. Variousmodifications may occur to those skilled in the art without departingfrom the true spirit and scope of the invention as defined by theappended claims.

I claim:
 1. A disc drive system comprising:a housing; a motor fixedwithin said housing; a fixed disc rotatably coupled to said motor whichrecords data and has a landing zone where no data is located; anactuator arm assembly further comprising voice coil magnets supportedfrom said housing; an actuator arm with a voice coil magneticallyattracted to said voice coil magnets such that said voice coil magnetsmove said actuator arm in response to electrical signals, said voicecoil being molded onto said actuator arm by an overmold; a flexurerigidly fixed to said actuator arm; a transducer fixed to an end of saidflexure opposite an end connected to said actuator arm; a landing zoneinertial latch means for preventing said transducer from leaving thelanding zone of said fixed disc when either a clockwise orcounterclockwise external shock is applied to said housing, comprising:a pair of protrusions held in place by said overmold; and an elongatedlatch element of non-magnetic material supported for rotation about apivot pin located immediately behind said voice coil and of sufficientlength to be rotated into contact with one of said protrusions whenrotating clockwise or counterclockwise; said protrusions being spaced onsaid voice coil overmold so that one of said protrusions cooperates withsaid latch element when either a clockwise or counterclockwise shockcauses motion of said actuator arm; said landing zone inertial latchmeans further comprises: a mass which is located beneath said voice coilof said actuator arm and has a means for maintaining said inertial latchmeans in a storage position during normal operation of said actuator armassembly; said elongated latch element is connected to said mass forrotating after a shock has occurred and for latching with one of saidprotrusions of said actuator arm and preventing said transducer fromleaving said landing zone; and wherein said landing zone inertial latchmeans is automatically aligned with said voice coil magnets by magneticleakage flux which attracts a magnetic insert supported in said mass. 2.The disc drive of claim 1 wherein said magnetic insert of said mass issteel.
 3. The disc drive of claim 1 wherein said mass is a non-magneticmaterial.
 4. The disc drive of claim 1 wherein said mass is made ofbrass.
 5. The disc drive of claim 1 wherein said means for maintainingsaid inertial latch means cooperates with said voice coil magnets tomaintain said actuator arm in a non-operating position in the absence ofshock.